Oxidation of petroleum ceresin and novel product obtained thereby



in a softening of the wax is disadvantageous.

United States Patent I OXIDATION OF PETROLEUM CERESIN AND NOVEL PRODUCTOBTAINED THEREBY Application December 31, 1953 SerialNo. 401,689

12 Claims. (Cl. 260-451) No Drawing.

This invention relates to a novel method for the oxidation of petroleumceresin and to the novel oxidized wax product obtainedthereby.

Previous methods of oxidizing petroleum ceresin have been generallyunsatisfactory in that they. produce oxidized wax compositions which aresubstantially softer than the original waxf At least in some uses ofoxidized ;microcrystalline waxes, such as oxidized petroleum ceresins,it is desirable that the oxidized wax be hard and in such cases, thetendency of prior art oxidations to result In the preparation ofoxidized microcrystalline wax for use in wax polishes, for example, itis particularly desirable to obtain a hard product. The presentinvention provides an improved oxidation process wherein an oxidized waxproductcan be obtained which is nearly as hard as, as

.hard as, or harder than the original wax previous to oxidation.

.Theoxidation method of the present invention is further advantageous in.that it produces an oxidized wax product having higher viscosity thanprior art oxidized waxes produced by previous oxidation methods. Suchhigher viscosity provides beneficial efiects as'subsequently -more fullydescribed, inthe use of oxidized petroleum ceresin in wax polishcompositions.

- I The novel oxidation method of the present invention involvesoxidation of a petroleum ceresin to a saponification number above 65with control of the rate of oxidation in order to obtain a low rate ofincrease in saponification number. The relatively slow'oxidationaccording to the invention produces the unexpected results of producinga hard oxidized wax with high viscosity, whereas the relatively fastoxidations of the prior art do not provide these beneficial-results;

The rate'ofoxidation according to the present invention is controlledwithin the range equivalent to 0.05 to 1.25 increase in saponificationnumber per hour. Oxidation rates below'the lower limit of the range aregenerally not economical, and oxidation rates above the upper limitgenerally result in failure to obtain the ading to theinventionf'generally result in a highratio of saponification number'toacid number, e. g. 3- to l0, and frequently in the neighborhood of 5.

The oxidation according to the present invention is continued until thesaponification number of the oxidized wax is above 65, since it has beenfound that the penetration of the oxidized wax generally increases within- I creasing saponification number in the early stages of theoxidation, and then after passingthrougha maximum, the penetrationceases to rise substantially and generally decreases with increasingsaponification number during the remainder of the oxidation; oxidationto a saponification number of 65-75 generally carries the oxidationbeyond the point of maximum penetration, SO that the beneficial effectof subsequent reduction in penetration is obtained, or at least so thatthe penetration levels oil and does not substantially increase upon,further oxidation. Generally, the most advantageous results according tothe invention are obtained by oxidizing to-a saponification number notabove 150, and preferably not above 100. The oxidation is preferablyterminated when the saponification number is within the range 75 to'150,

' vention under those other oxidation conditions. Factors morepreferably not above 100. At a typical rate of saponification numberincrease, 0.35 per hour, the time required to obtain saponificationnumber in the range to 150 is about 210 to 420 hours.

The required oxidation rate according to the invention can be obtainedby proper selection of the various conditions which affect the oxidationrate, such as temperatures, catalyst, catalyst concentration, air rate,air-wax contacting conditions, etc. In the light of the presentspecification, aperson skilled in the art canselect the conditions whichwill provide a saponification number increase within the required rangeof 0.05 to 1.25 per hour. Generally suitable temperatures will be foundwithin the range from the lowest temperature at which the wax is molten,up to about 300* F., and generally suitable air rates within the rangeof 1000 to 5000 cc./ minute/1000 grams of wax. It is to be understood,of course, that other free-oxy'gen-containing gases can be used insteadof air; exceptions, however, are sometimes noted in the case of aircontaining substantial amounts, e. g. as much as one percent, of ozone.Such ozonized air has been found to be unsuitable for producing theadvantageous results of oxidation according to the present invention;and therefore the oxygen containing gases used should be substantiallyfree from ozone, though some small ozone contents may not bedetrimental.

The air-wax contacting conditions have a substantial effect on theoxidation rate, and 'it is possible to obtain the relatively slowoxidation rate according to the invention with contacting conditionswhich do not provide very intimate contact between oxygen and wax, eventhough the other oxidation conditions are such that intimate contactbetween oxygen and wax would result in a'higher oxidation rate than thatof the present ininvolved in the air-wax contacting conditions include,in a process Where air is bubbled through liquid Wax, the number andsize of the air bubbles, the degree of mechanical agitation if any, etc.1

Oxidation according to the present invention is preferably conducted inthe presence of a catalyst, e. g. a

catalyst of the drier type, as employed in paints and varnishes, etc.Metallic soaps such as manganese, cobalt, lead, or zinc soaps ofnaphthenic, stearic, oleic, palmitic, or linoleic acids, etc., aresuitable catalysts of the drier type. Manganese soaps are particularlypreferred The amount of catalyst employed is preferably such asptoprovide 0.02 to 2.0 parts by weight of metal,

e. g. manganese, per parts of wax. V

,oxidized microcrystalline wax product characterized by low penetration,high ratio of saponification number to acid number, and high viscosity.The penetration at 77F. is not greater than 10, the ratio ofsaponification number to acid number is at least 3, and the S. U.viscosity at 210 F. is at least 200. The saponification num- "ber isabove 65 and preferably in the range 75 to 150.

Prior tothe present invention, oxidized wax products characterized bylow penetration and high ratio of saponification number to acid numberhave been known, but these priorart products have had lower viscositiesthan the oxidized wax products of the present inven- "tion. The highviscosity of the products according to 'thepresent invention isparticularly advantageous in use of the products in wax polishcompositions, where an unusually high gloss and resistance to scuflingand slipping is provided by virtue of the high viscosity of theproducts.

The oxidized wax products of the invention may have any penetration at77F. not greater than 10, though generally the penetration will be atleast 1, and generally in the range'2 to 8. Also, the ratio ofsaponification' number to acid number will generally not be greater than10. The S. U. viscosity of the oxidized wax according to the inventioncan vary widely, because of the rapid increase'of viscositywith timewhich is obtained in the novel oxidation according to the method of theinvention;.thus very high viscosity products, even above 1000 S. U.viscosity at 210 F. can be obtained with longoxidation periods. Highlyadvantageous oxidized wax products according to the invention are thosehaving S. U. viscosity at.2l F. above 300, more preferably above 500.Generally, the most suitable oxidized waxes will-not have S. U.viscosity at 210 F. above 2000 "though such oxidized waxes can and havebeen prepared according to the invention.

The-following examples illustrate the invention:

Example 1 Inthis example, a petroleum ceresin wax oxidized underconditions to provide an average increase in saponification number ofabout 0.36 per hour and an average increase in acid number of about 0.09per hour. The total oxidation period was 268 hours, and thesaponidication number and acid number of the product were 95.3 and 22.6respectively.

The :oxidation charge was a petroleum ceresin pre- ,pared byde-waxing asolvent-refined lubricating oil to obtain slack wax, distilling oif 70percent of the slack wax, andde-oiling the residue by dissolving in asolvent 1 comprising-methyl ethyl ketone, benzene, and toluene at atemperature above 92 F., cooling to92 F., and filtering to obtain afilter cake which after removal of .,so1vent.and decolorization withclay at 300 F. yielded glass spiders, was bubbled upwardly through themolten wax and then withdrawn from the vessel. The air rate for thefirst 46.75 hours was 3000 cc. per minute per 1000 grams of wax, and forthe remainder of the oxidation was 2000 cc. per minute per 1000 grams ofwax.

, Theoxidation' was'conducted in the presence of a man- :ganesenaphthenate catalyst in amount equivalent to 0.04 part of manganese per'100 parts of wax. During the oxidation periodic measurements were madeof the 4" l properties of the oxidized wax. The following table showsthe variation of properties with time:

Sapomfi- Acid Penetra- Viscosity, 5 Time in Hours cation Number tion atS. U. V.

Number 77 F. at 210 F.

The oxidation was terminated at'the end of the 268 hour period. Themelting point of the product was 175 F. The table shows that thepenetration increased during a first portion of the oxidation period anddecreased duringa last portion of the oxidation period to give anultimate product having penetration only one point higher than that ofthe original .unoxidized wax. The low penetration of the product is anunobvious and highly advantageous property for oxidized waxes for use inpolishes and other applications.

Example 2 In the preceding example, the penetration of the oxidized waxat saponification number of 95.3 was only one point higher than that ofthe original wax. In many instances according to the invention, thepenetration of the .oxidized wax at saponification number above 65 willbe no higher at all than that of the original wax. For example inoxidation of a wax difiering from that oxidized in the previous exampleonly in that the present wax had not been decolorized with clay, it wasfound that after oxidation for 235.25 hours, the saponification numberhad increased from 0 to,88.2 and the penetration had-after increasingfrom 5 to 8 in the early stages of the oxidation, decreased again to 5.

Comparison Example 1 In order to compare the oxidation procedure andproduct with other procedures and products not providing the unusualresults obtained according to the present invention, the same wax usedin Example 1 was oxidized in the presence of the same catalyst as inExample 1, the air rate being 4500 cc. minute/ 1000 grams of wax, andthe oxidation temperature being 290-300 F. The air was introduced intoa' lower portion of the body of liquid wax through two fritted glassdifiusers, rather thanthrough the two glass spiders employed inExample 1. The etfect of the use of such difiusers was to produce alarger number of air bubbles of smaller size, and 'to provide moreagitation of the liquid wax, than in Example 1.

Because of the higher temperature and air rate and the more intimatecontactof air with wax, the oxidation rate in the present example washigher than in Example 1. The following table shows the variation ofproperties with time:

\ Saponifi- Penetration Time In Hours cation at 77F.

Number The above table shows that the rapid oxidation of the Vcomparison example results in a steadily increasing penetration which is24 at a saponification numb?! of 138.9

Example 1 Comparison Example Average Sap. N0. Increase/Hr 0.356 6. 7Penetration (77 F.) at 94.3-95.3 Sap. No 7 16 From the above table, itis seen that oxidation according to the present invention provides amuch harder wax from a given charge stock than does a more rapidoxidation of the type employed in the prior art. The oxidation accordingto the present invention also provides an oxidized wax product havingmuch higher viscosity than that obtained by a more rapid oxidation. Thisis shown by the following Comparison Example 2.

Comparison Example 2 Example 1 Comparison Example 2 Average Sap. N0.Increase/Hr 0.356 3. 55 Maximum S. U. V. at 210 F 841 156 The abovetable shows that oxidation according to the present invention provides amuch higher viscosity product than a more rapid oxidation of the typeemployed in the prior art.

In Examples 1 and 2 and the comparison examples, the difference inoxidation rates was obtained partly by virtue of a difierent manner ofintroducing the oxidizing agent into contact with the wax. Thedecelerating effect of introducing the air in the manner of Examples 1and 2 is probably due to the smaller amount of surface area of contactbetween airbubbles and wax, the bubbles being larger and less numerousthan in the comparison examples, and to the lesser agitation provided bythe air introduction method of Examples 1 and 2. It is to be understoodthat other methods of providing a relatively slow oxidation can beemployed. For example, using the air introduction apparatus of thecomparison example, the air could be introduced at a lesser volume ratein order to provide a slower rate of oxidation that would provide theadvantageous results obtained in Examples 1 and 2. Other variables, suchas oxidation temperature and catalyst, can be regulated in order toprovide the proper rate of oxidation. In the light of the presentspecification, a person skilled in the art can determine the oxidationconditions to provide the proper rate of oxida-' tion.

Oxidized waxes obtained according to the present invention have noveland advantageous combinations of properties in that they have highratios of saponification to acid number, low penetrations, and highviscosities. Prior art oxidized waxes do not have this advantageouscombination of properties. This is demonstrated in the following tablewhich presents a comparison of proper ties between several prior artoxidized Waxes and two oxidized waxes according to the presentinvention, oxidized wax 1 being the product obtained in Example 1,

and oxidized wax 2 being another product obtained by the process of thepresent invention:

Saponifi- Acid Penetra- Viscosity cation Number tion at at210 F. Number77 F.

Prior Art Waxes:

78 28 162 76 28 9 V 123 C 53 24 114 Waxes According to the Invention:

As seen from this table, the oxidized waxes according to the presentinvention have much higher viscosities than those of prior art oxidizedwaxes. v

In the preceding description of examples, the oxidized wax productreferred to is the total liquid oxidation product, with no separation ofthe liquid oxidation product into various types of components such asoxidized ma terial and unoxidized material, etc. It is to be understoodthat such separations can be effected after an oxidation according tothe present invention but such oxidation has particular advantage in thepreparation of oxidized wax products where the total oxidation productis employed, e. g. in a wax polish composition.

Penetrations given herein were determined by A. S. T. M. standard methodof test D5-25 under the standard conditions of grams, 5 seconds, 77 F.Acid numbers were determined by A. S. T. M. standard method of testD974-51T. Saponification numbers were determined by the procedure of A.S. T. M. standard method of test D94-48T except that toluene was used assolvent in place of methyl ethyl ketone.

This application is a continuation-in-part of copending applicationSerial No. 311,144 of Seymour W. Ferris and Herbert L. Johnson, filedSeptember 23, 1952, and now abandoned.

The invention claimed is:

1. Method for obtaining oxidized petroleum ceresin having lowpenetration and high viscosity which comprises: oxidizing a petroleumceresin having melting point within the approximate range from F. to 210F. at an average rate equivalent to 0.05 to 1.25 increase insaponification number per hour for the period required to reach asaponification number of 65; and terminating the oxidation when thesaponification number of the total oxidation product is above 65 and thepenetration of the oxidized wax at 77 F. is less than it was at anearlier stage of the oxidation.

2. Method according to claim 1 wherein the average rate of acid numberincrease per hour is 0.1 to 0.30.

3. Method according to claim 1 wherein the total oxidation time iswithin the range 210 to 420 hours.

4. Method according to claim 1 wherein the oxida-- tion is conducted inthe presence of a drier catalyst.

5. Method according to claim 4 wherein said catalyst is manganesenaphthenate in amount equivalent to 0.02 to 2.0 parts by weight ofmanganese per 100 parts of wax.

6. Method according to claim 1 wherein said oxidation is conducted withthe wax in molten state at a temperature not substantially above 300 F.

7. Method according to claim 1 wherein said wax is oxidized by contactwith air at a rate of 1000 to 5000 cc. of air per minute per 1000 gramsof wax.

8. Method according to claim 7 wherein said contact is obtained bypassing large bubbles of air through a body of said wax in molten state.

9. An oxidized ceresin composition having saponification number of above65, ratio of saponification number to acid number of at least 3,penetration at 77 P. not greater than 10, and S. U. viscosity at 210 F.of at least 200.

10. Composition according to claim 9 wherein said viscosity at 210 F. isat least 500.

11. Method for obtainingyoxidized petroleum ceresin is terminated whenthe saponification numberof'thetotal -having low penetration and-highviscosity which conloxidation product is above 75 mg. of KOH: per; gram.prises: oxidizing a-petroleum ceresin having melting point 1 1th1ntherapproximate range from 175 F. to 210 F. Refemmessited in themeofthispatent V to asaponification number of at least 65 mg. of KOH pergram at a rate such that the saponification number UNITED STATES PATENTS*reaches 65 withingabout 140 to 1300 hours; and terminat- 1,983,672Labarthe et a1. Dec. 11, 1934 'ing the oxidation, when the penetrationof the oxidized 2,119,940 Carr et a1. June 7, 1938 wax at77" F. is lessthan it was-atan-earlier stage of the 2,662,864 Rumberger Dec. 15, 1953oxidation. 10 2,674,613 Nelson Apr; 6, 1954 12. Method according toclaim 1 wherein the oxidation 2,681,357 McKinley June 15, 1954

1. METHOD FOR OBTAINAING OXIDIZED PETROLEUM CERESIN HAVING LOWPENETRATION AND HIGH VISCOSITY WHICH COMPRISES: OXIDIZING A PETROLEUMCERESIN HAVING MELTING POINT WITHIN THE APPORXIMATE RANGE FROM 175*F. TO210*F. AT AN AVERAGE RATE EQUIVALENT TO 0.05 TO 1.25 INCREASE INSAPONIFICATION NUMBER PER HOUR FOR THE PERIOD REQUIRED TO REACH ASAPONIFICATION NUMBER OF 65; AND TERMINATING THE OXIDATION WHEN THESAPONIFICATION NUMBER OF THE TOTAL OXIDATION PRODUCT IS ABOVE 65 AND THEPENETRATION OF THE OXIDIZED WAX AT 77*F. IS LESS THAN IT WAS AT ANEARLIER STAGE OF THE OXIDATION.